Rotating systems, such as gear systems or bearing support systems, of wind turbines require lubrication by special lubricants, e.g. in the form of greases or oils. It is well known that the rotating parts in such systems cause slip streams in the lubricant. These slip streams may potentially disturb the lubricant circulation, with noticeable negative impact on the operation of the rotating system.
Accordingly, it is desirable to design rotating systems in a manner which minimises the lubricant slip streams. On the other hand, in modern wind turbines it is desirable to minimise the outer dimensions of large components, including gear system and bearing support systems, in order to be able to accommodate the components in the nacelle of the wind turbine. This may be obtained by minimising the distance between moving and non-moving parts of the rotating system. However, this aggravates the slip stream problem described above.
GB 1 359 321 discloses a transmission unit having coaxial input and output members. A non-rotatable lubricant-feed member through which an arbor extends is located between the input and output members and is arranged to receive lubricant from splashing or spray within a casing and convey the lubricant to the surface of the arbor at a region at which its diameter is not greater than that of its journals. The lubricant is directed along the surface of the arbor to the interior of the bore. The lower part of the gearcase is widened to act as a sump to contain lubricating oil into which the lower extremities of the layshaft gears dip.
U.S. Pat. No. 6,021,868 discloses a cooling and lubrication system for a mechanical change gear transmission including a first conduit for providing pressurized lubricating fluid from the engine and a second conduit for returning lubricating fluid to the engine. Lubrication may be provided in a dry-sump operating arrangement through a manifold which distributes lubricating fluid among transmission components. A splash lubrication arrangement controls the level of lubricating fluid by appropriate positioning of the transmission outlet port.